十八难曰∶脉有三部，部有四经，手有太阴、阳明，足有太阳、少阴，为上下部，何谓也？
然∶手太阴、阳明，金也；足少阴、太阳，水也；金生水，水流下行而不能上，故在下部也。足
厥阴、少阳，木也；生手太阳、少阴火，火炎上行而不能下，故为上部。手心主、少阳火，生足太阴、
阳明土，土主中宫，故在中部也。此皆五行子母更相生养者也。
脉有三部九候，各何主之？然∶三部者，寸关尺也。九候者，浮中沉也。上部法天，主胸以上至
头之有疾也；中部法人，主膈以下至脐之有疾也；下部法地，主脐以下至足之有疾也。审而刺之者也。
人病有沉滞、久积聚，可切脉而知之耶？
然∶诊在右胁有积气，得肺脉结，脉结甚则积甚，结微则气微。
诊不得肺脉，而右胁有积气者何也？然∶肺脉虽不见，右手脉当沉伏。
其外痼疾同法耶？将异也？
然∶结者，脉来去时一止，无常数，名曰结也。伏者，脉行筋下也，浮者，脉在肉上行也。左右表里，
法皆如此。
假令脉结伏者，内无积聚；脉浮结者，外无痼疾；有积聚脉不结伏，有痼疾脉不浮结。为脉不应病
，病不应脉，是为死病也。
十九难曰∶经言脉有逆顺，男女有恒。而反者，何谓也？
然∶男子生于寅，寅为木，阳也。女子生于申，申为金，阴也。故男脉在关上，女脉在关下，是以
男子尺脉恒弱，女子尺脉恒盛，是其常也。
反者，男得女脉，女得男脉也。其为病何如？
然∶男得女脉为不足，病在内；左得之病在左，右得之病在右，随脉言之也。女得男脉为太过
，病在四肢；左得之病在左，右得之病在右，随脉言之，此之谓也。
Chapter 18 states: The pulse is divided into three positions (Cun, Guan, Chi), and each position corresponds to four meridians. The hand has the Taiyin (Lung) and Yangming (Large Intestine) meridians; the foot has the Taiyang (Bladder) and Shaoyin (Kidney) meridians. These are referred to as the upper and lower parts. What is the reason for this?
The answer is: The Hand-Taiyin Lung Meridian and Hand-Yangming Large Intestine Meridian belong to Metal; the Foot-Shaoyin Kidney Meridian and Foot-Taiyang Bladder Meridian belong to Water. Metal generates Water, and water flows downward and cannot ascend; therefore, they are located in the lower part. The Foot-Jueyin Liver Meridian and Foot-Shaoyang Gallbladder Meridian belong to Wood; Wood generates the Fire of the Hand-Taiyang Small Intestine Meridian and Hand-Shaoyin Heart Meridian. Fire flares upward and cannot descend; therefore, they constitute the upper part. The Hand-Jueyin Pericardium Meridian and Hand-Shaoyang Sanjiao (Triple Burner) Meridian belong to Fire; Fire generates the Earth of the Foot-Taiyin Spleen Meridian and Foot-Yangming Stomach Meridian. Earth governs the Central Palace (Middle Jiao); therefore, they are in the middle part. These all illustrate the mutual generation and nourishment between mother and child elements within the Five Phases (Wu Xing).
Regarding the three positions and nine inspections (Fu, Zhong, Chen) of the pulse, what does each primarily indicate? The answer is: The three positions refer to Cun (Inch), Guan (Bar), and Chi (Cubit). The nine inspections refer to superficial (Floating), moderate (Medium), and deep (Sinking) palpation. The upper position models Heaven and indicates diseases from the chest up to the head; the middle position models Humanity and indicates diseases from below the diaphragm to the umbilicus; the lower position models Earth and indicates diseases from below the umbilicus to the feet. One must examine them carefully before applying acupuncture.
Can one know if a patient suffers from stagnant conditions or long-standing accumulations through pulse diagnosis?
The answer is: If there is an accumulation of Qi in the right hypochondrium, and a Jie (Knotted) pulse of the Lung meridian is obtained, the more severe the knottedness, the greater the accumulation; the slight the knottedness, the lesser the Qi stagnation.
What if the Lung pulse does not show a Jie pattern, yet there is an accumulation of Qi in the right hypochondrium? The answer is: Although the Lung pulse does not appear knotted, the pulse on the right hand should be Fu (Deep/Hidden).
Is the method for external chronic illnesses the same? Or is it different?
The answer is: "Jie" refers to a pulse that stops occasionally during its coming and going, without a fixed number, known as a Knotted pulse. "Fu" means the pulse travels beneath the tendons (deep). "Fu" (Floating) means the pulse travels above the flesh (superficial). The principles for left/right and interior/exterior are applied similarly.
If the pulse is Jie or Fu, but there is no internal accumulation; or if the pulse is Floating or Jie, but there is no external chronic disease; if there is an accumulation but the pulse is not Jie or Fu, or if there is a chronic disease but the pulse is not Floating or Jie—this constitutes a mismatch between pulse and disease, and disease and pulse, which indicates a fatal condition.
Chapter 19 states: The classics mention that pulses have contrary and compliant patterns, and men and women have constant norms. What does it mean when these are reversed?
The answer is: Men are associated with Yin month, where Yin represents Wood and Yang energy. Women are associated with Shen month, where Shen represents Metal and Yin energy. Therefore, in men, the pulse is prominent at the Guan position (upper/middle), while in women, it is prominent at the Chi position (lower). Thus, the Chi pulse in men is typically weak, while the Chi pulse in women is typically strong; this is the normal state.
Reversal refers to men obtaining women's pulse characteristics, and women obtaining men's pulse characteristics. What kind of illness do they suffer?
The answer is: When a man obtains a woman's pulse (strong Chi), it indicates deficiency, with disease located internally. If found on the left, the disease is on the left side; if on the right, the disease is on the right side, determined by following the pulse location. When a woman obtains a man's pulse (weak Chi), it indicates excess, with disease located in the four limbs. If found on the left, the disease is on the left side; if on the right, the disease is on the right side, determined by following the pulse location. This is what is meant.